The present invention relates to a paging system having an automatic dialing function, and more particularly to a paging system which can automatically dial a telephone number including an area code.
Generally, in a compact paging receiver, an alert tone is generated in response to a radio calling signal remotely received and, a telephone number of a caller is transmitted with the alert tone. Data applied to the paging receiver has a specific code form, such as a POCSAG (Post Office Code Standardization Advisory Group) code. In the POCSAG code, one data batch consists of 8 frames. Each frame consists of an address code word which indicates a specific address of the paging receiver and a message code word to which the telephone number of the caller is conveyed.
FIG. 1 is a block diagram of a conventional paging system and FIG. 2 is a flow chart for showing the function of automatic dialing in the conventional paging system. A control circuit 120 drives a receiver 110 a frame period and the receiver 110 demodulates a received radio frequency signal to shape a waveform thereof and applies the shaped signal to the control circuit 120. The control circuit 120 is a one chip microprocessor unit which has a program ROM (Read Only Memory), a RAM (Read Access Memory) 121 for storing received data and a DTMF (Dual Tone Multi-Frequency) generator 122 for generating the stored data as a DTMF signal.
When the control circuit 120 is supplied with data from the receiver 110, the control circuit 120 checks whether the data is data of the paging receiver by analyzing the address code word. If the data is data of the paging receiver, the control circuit 120 stores the telephone number of the message code word into the RAM 121 by the use of a memory key 140. When a user makes a phone call under the above condition that the telephone number is stored in the RAM 121, the user depresses a read key 150. In this case, the control circuit 120 detects the depression of the read key 150 in a step 202, reads from the RAM 121 the telephone number corresponding to the number of depressing the read key 150 and displays the telephone number on a LCD (Liquid Crystal Display) 130, through steps 204, 206 and 208 as shown in FIG. 2. Thereafter, if the user confirms the telephone number and depresses a dial key 160, the control circuit 120 detects the depression of the dial key 160 in a step 210 and converts the telephone number displayed on the LCD 130 into the DTMF signal through the DTMF generator 122. FIG. 1 shows a speaker 170 which generates the DTMF signal as a DTMF tone. The speaker 170 has to be located beside a transmitter of an electronic exchange, and the DTMF tone output from the speaker 170 is applied to the electrical exchange through a telephone transmitter. Therefore, the user dials a telephone number using the paging receiver without performing a conventional dialing operation.
The above system has shortcomings. Since the area code of a caller or the current place of a user, etc. were not considered, when using the area code, if the user performs automatic dialing with the received telephone number, the telephone call is errant. Therefore, the loss of time occurs because the user must use keys of the telephone without using an automatic dial. Also, when an extension number of the caller in the received telephone number is included, if there is no an editing function, an unnecessary DTMF signal is generated when performing automatic dialing. Further, if power to the paging receiver is turned off, the stored telephone numbers are erased, requiring manual reinput of telephone numbers.